Rebuilt with JDK 1.5 and build succeeded. So if I'm understanding correctly it seems that classes compiled with JDK 1.5 and included in .jars cause problems for people running JDK 1.4.
I should note that I'm haven't used Maven before, so it's unclear to me how anything involving JDK 1.5 made it onto my system when I'm doing a complete build locally under JDK 1.4 (which was working fine until recently)...
